Van Rooyen, 28, carded the best round of the week so far as he signed for a 65 with first-round leader Fox, son of All Blacks great Grant Fox, notching a 69 and Pavon, 25, posting a second 68.

The trio lead Sweden’s Joakim Lagergren by a stroke while 2016 Masters champion Danny Willett is in a group two off the pace as he continues to show signs of improved form.

Defending champion Jon Rahm made it through to the weekend after a 69 left him sharing 30th place with McIlroy on one under but Padraig Harrington – one behind Fox overnight – missed the cut by a shot as a double bogey at the last saw him signing for a 78.

McIlroy hit by horrible horseshoe

Having started at the 10th, tournament host McIlroy’s day on the greens was summed up by his 20-foot birdie effort on the 18th being denied by a horrible horseshoe out of the cup.

“I definitely hit my best putt on the week on 18 this morning and it came straight back at me so that was nice,” said McIlroy with an ironic laugh.

Having missed seven putts inside 10 feet in Thursday’s opening 70, McIlroy spurned an eagle chance from similar range at the par-five fourth and left several other birdie efforts short.

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‘It tested my patience’ – McIlroy

For the second day in succession, McIlroy found the deep bunker to the left of the par-three fifth and his initial failure to get out of the trap resulted in his second bogey, after his earlier dropped shot at the 16th.

A delightful sand wedge to a tight front pin on six was converted but he bogeyed the eighth after running out of fairway on his tee shot before missing from 10 feet for par at the last when a wild drive was followed by carving his second shot into greenside rough.

Tournament host targets two closing 68s

Despite his disappointing finish, McIlroy still believes that heading into the weekend, he can repeat his 2016 K Club triumph.

“I’ve hit the ball well from tee to green which is something I was struggling with the last couple of weeks so I’m more comfortable with my swing,” added the world number eight.

“I’d say if I shot two 68s over the weekend, I don’t think I’d be too far away.”

Despite perfect weather conditions at the Donegal venue, Ballyliffin again proved a tough test with pre-tournament predictions that 20-under-par or perhaps even lower could be the winning score on Sunday, now looking fanciful.

Harrington’s hopes of adding to his 2007 Irish Open win were extinguished by his error-ridden 78 which included a lost-ball seven at the long 13th in addition to his calamitous final hole.

The twice Open champion looked set to survive after an unlikely 40-foot birdie on 16 was followed by another gain at the long 17th.

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Willett gets reward for hard graft

However, the latest in a series of dreadful drives saw him hitting a sand dune with his second shot at the 18th and he then three-putted from 40 feet to crash out of the tournament.

Englishman Willett, now a lowly 442nd in the world rankings following a major slump after his Augusta triumph, continued his improved recent form with a five-birdie round which left him two off the pace with compatriot Sam Horsfield and another South African Zander Lombard.

Lee Westwood is a shot further back after adding a 71 to his opening 68 with Scotland’s Russell Knox among those four off the pace.

Shane Lowry and Simon Thornton are the leading Irishmen – six off the pace on two under after rounds of 70 – while Graeme McDowell survived on level par after a 73 with Paul Dunne squeezing into the final two days on one over.

Italy’s 2010 European Ryder Cup player Edoardo Molinari had a hole in one at the 14th but, like Harrington and another Irishman Ruaidhri McGee, dropped two shots at the last to miss the cut by one stroke.

In the first staging of the event at the venue, Friday’s 18,904 attendance brought up the crowd figure so far this week to just over 44,000 and the organisers will now have high hopes of exceeding 80,000 for the week.